Signs of hope in battle against water chestnut weed in Nashua River

By DAVID BROOKS

Staff Writer

NASHUA – The battle against water chestnuts growing in the Nashua River will resume this month, with volunteers needed to paddle out and start uprooting them June 14 amid hopes that the tide has turned against this nasty invasive weed.

“It’s very hard to move toward eradication, but the goal is to reduce it enough that it can be addressed by volunteer pulls,” said Kathryn Nelson, water monitoring coordinator for the Nashua River Watershed Association. ...
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NASHUA – The battle against water chestnuts growing in the Nashua River will resume this month, with volunteers needed to paddle out and start uprooting them June 14 amid hopes that the tide has turned against this nasty invasive weed.

“It’s very hard to move toward eradication, but the goal is to reduce it enough that it can be addressed by volunteer pulls,” said Kathryn Nelson, water monitoring coordinator for the Nashua River Watershed Association.

“We hope we’re at that point in Nashua.”

But Nelson added that it’s no time to celebrate.

“This is a weed,” she said. “It’s like your lawn – you may feel, ‘There’s not as many dandelions this year, I guess I’ve got them under control.’ Then you look out one day and your yard is again covered with them.”

Water chestnut – no relation to the Chinese restaurant staple of the same name – is an Asian aquatic weed with floating leaves that block sunlight and has spiky nuts that can lie on the river bottom and stab swimmers’ feet. It is a huge problem in the Nashua River upstream in Pepperell, Mass., where the Pepperell Ponds are badly choked by it.

Both infestations are upstream from dams. Water chestnut needs slack water to thrive, and is often found near dams, which slow the flow of a river.

Water chestnut was first spotted in Nashua in 1998, probably because seeds floated downstream. Within a decade, the plant formed large mats covering up to 35 acres and threatened to choke off the river.

Nashua has spent around $30,000 each of the last three summers to hire a floating mechanical harvester from Aquatic Control Technologies, which has pulled up hundreds of tons of weeds.

Nelson said city officials and monitors would determine whether mechanical harvesting was necessary again this year.

“I think the city’s being smart, keeping (Aquatic Control Technologies) on retainer if it is needed,” she said. “Pepperell needs many years of harvesting at a large scale, but it does not have any comparable funding … like Nashua does.”

The city has also put out barrels by canoe launching areas so people can deposit plants they pull up.

Volunteers are needed from 9 a.m.-noon June 14 to scout and pull water chestnuts from the Nashua River upstream of the Mine Falls dam.

Similar volunteer pulls have been conducted in recent summers, but this is the first overseen by the watershed association, which has run similar events for a decade upstream in Pepperell.

The main goal will be to find and pull up smaller clumps of the just-emerging plant along the edge of the river.

“The hope is that the main, large mass won’t be re-emerging,” Nelson said.

A similar volunteer pull will be held later this summer in Pepperell – the 10th annual such event.